Back in 2000, I started my network exploration with tcpdump -> Ethereal -> Wireshark / TShark. Wonderful set of network protocol analyzer tool. I know Libpcap little bit. But I understood the background about it from the SharkFest 2011 video, about the Libpcap by Steve McCanne, creator of libpcap and co-founder of RiverBed. Steve nicely explained, How the packet capturing problem went from Network Programming to Compiler Design and then to Graph Theory. Apart from this, there are many useful presentations are available in the SharkFest site.